Needle mechanism module for drug infusion device

ABSTRACT

A needle mechanism module for drug infusion device, includes: an infusion needle, provided with a front end and a rear end; a needle holder; provided with at least an auxiliary engaging part, the infusion needle being arranged on the needle holder, when the needle holder is at the working position, the rear end is inserted into the skin, and the front end is connected to the drug storage unit of the infusion device; an auxiliary engaging portion, arranged within the infusion device, engaged with the auxiliary engaging part to limit the needle holder at the working position; and a stopper, arranged on the housing of the infusion device, when the needle mechanism module is at intermediate position, the stopper limits the position of the needle holder, the front end is connected with the drug storage unit of the infusion device, to balance the internal and external pressures.

TECHNICAL FIELD

The present invention mainly relates to the field of medical instruments, in particular to a needle mechanism module for drug infusion device.

BACKGROUND

A drug infusion device can continuously deliver drug into a patient's body for disease treatment. Drug infusion devices are widely used in the field of diabetes treatment, which continuously infuse required dosage of insulin into the patient's subcutaneous tissue, thereby simulating the secretion function of the pancreas to keep the blood glucose stable. The drug fluid is usually stored inside the infusion pump. The drug infusion device in prior art, controlled by remote device, is usually attached directly on the patient's skin through a medical adhesive tape.

At present, during the infusion process of the existing drug infusion device, due to the imbalance of the internal and external pressure, or non-full and improper priming of the fluid path or all the air in the infusion needle cannot be exhausted in time during the infusion process, causing the air infused under the skin, which affects the health of the user and poses a safety risk.

Therefore, in the prior art, there is an urgent need for a needle mechanism module for drug infusion device to balance the internal and external pressures, fully and properly prime the fluid path, and exhaust all the air in the infusion needle in time.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention provide a needle mechanism module for drug infusion device. The needle mechanism module comprises a stopper, the stopper limits the position of the needle holder, when the needle mechanism module is at intermediate position, the front end is connected with the drug storage unit of the infusion device, to balance the internal and external pressures, when the infusion unit is activated, the drug can enter the infusion needle to prime the fluid path and exhaust all the air from the infusion needle, preventing air from being infused into subcutaneous, which eliminates safety hazards and improves user experience.

The invention discloses a needle mechanism module for drug infusion device, comprising: an infusion needle, provided with a front end and a rear end; a needle holder, provided with at least an auxiliary engaging part, the infusion needle being arranged on the needle holder, when the needle holder is at the working position, the rear end is inserted into the skin, and the front end is connected to the drug storage unit of the infusion device; an auxiliary engaging portion, arranged within the infusion device, engaged with the auxiliary engaging part to limit the needle holder at the working position; and a stopper, arranged on the housing of the infusion device, when the needle holder is at the non-working position, the stopper limits the position of the needle holder.

According to one aspect of this invention, the needle holder includes a guide post which can move along a guide cavity that is provided in the housing of the infusion device.

According to one aspect of this invention, the auxiliary engaging part is arranged on the guide post or under the top of the needle holder, and the auxiliary engaging part or the auxiliary engaging portion is one or a combination of hook, hole, block, or slot.

According to one aspect of the present invention, a slider is provided on the stopper while the housing is provided with a sliding groove, the slider is arranged in the sliding groove, and the slider can slide along the sliding groove to make the stopper engage or release the needle holder.

According to one aspect of the invention, at least one engaging arm is provided on the stopper.

According to one aspect of the invention, it further comprises an engaging portion, and the first engaging portion is provided on the engaging arm to engage with the needle holder to limit the position of the needle holder.

According to one aspect of the present invention, the side surface of the guide post is provided with convexes or concaves, the engaging arm engaged with the convexes or concaves to limit the position of the needle holder.

According to one aspect of the present invention, the thickness of the forward end of the stopper is smaller than the thickness of the backward end of the stopper.

According to one aspect of the present invention, the stopper is provided with an unlock rod.

According to one aspect of the present invention, it further comprises a unlock hole, the opening of the unlock hole is provided on the top of the needle holder or the housing, or on the side wall of the housing, the unlock rod releases the engagement of the auxiliary engaging part and the auxiliary engaging portion through the unlock hole.

According to one aspect of the present invention, the opening of the unlock hole is provided on the top of the needle holder, and the longitudinal directions of the unlock hole and the guide post are parallel to each other.

According to one aspect of the present invention, the mode for forcing to release and reset the needle holder includes a pop-up mode or a pushing mode.

According to one aspect of the present invention, it further includes a spring, arranged in the guide cavity, which is compressed by the needle holder when the needle holder is at the working position.

According to one aspect of the present invention, it further includes a locking lever, the auxiliary engaging part is a hole or a slot, the first end of the locking lever is movably arranged inside the auxiliary engaging part while the second end is engaged with the auxiliary engaging portion, the fulcrum of the locking lever is arranged between the two ends of the locking lever, and the second end is pushed by the unlock rod to move a certain distance to release the engagement of the auxiliary portion and the locking lever and release the needle holder.

Compared with the prior arts, the technical solution of the present invention has the following advantages:

In the needle mechanism module for drug infusion device disclosed herein, the needle mechanism module comprises a stopper, the stopper limits the position of the needle holder, when the needle mechanism module is at intermediate position, the front end is connected with the drug storage unit of the infusion device, to balance the internal and external pressures, when the infusion unit is activated, the drug can enter the infusion needle to prime the fluid path and exhaust all the air from the infusion needle, preventing air from being infused into subcutaneous, which eliminates safety hazards and improves user experience.

Furthermore, the side surface of the guide post is provided with convexes or concaves, the engaging arm engaged with the convexes or concaves to limit the position of the needle holder, to ensure the needle holder is limited at the non-working position.

Furthermore, a slider is provided on the stopper while the housing is provided with a sliding groove, the slider is arranged in the sliding groove, and the slider can slide along the sliding groove to make the stopper engage or release the needle holder more conveniently.

Furthermore, the thickness of the forward end of the stopper is smaller than the thickness of the backward end of the stopper, when sliding the stopper forward to realize the limit engagement and backward to release the limit engagement, it fits more closely with the fingers, which saves more effort and improves the user experience.

Furthermore, a spring is arranged in the guide cavity, which is compressed by the needle holder when the needle holder is in the working position. Once the spring is set, the needle holder can pop-up and be automatically reset after being released, which optimizes the releasing and resetting process and facilitates the user's operation. Meanwhile, before the infusion device is torn off from the skin, the rear end of the infusion needle can be retracted into the housing by the spring to avoid scratching the skin and improve user experience.

Furthermore, it further includes a locking lever, the auxiliary engaging part is a hole or a slot, the first end of the locking lever is movably arranged inside the auxiliary engaging part while the second end is engaged with the auxiliary engaging portion, the fulcrum of the locking lever is arranged between the two ends of the locking lever. The fulcrum is arranged between the two ends, making the movement direction of the two ends opposite. Therefore, while the second end is pushed by the unlock rod, the first end can move to force the needle holder out, that is, the needle holder can be reset without spring, which enhances the dexterity of internal structure.

Furthermore, the opening of the unlock hole is provided on the top of the needle holder, and the longitudinal directions of the unlock hole and the guide post are parallel to each other. The two parallel longitudinal directions make user just only apply a small force to release the needle holder, simplifying the operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic view of a part of the structure of the infusion device according to an embodiment of the present invention;

FIG. 1 b is a schematic view of the needle mechanism module taken along the section line A-A′ in FIG. 1 a;

FIG. 1 c is a schematic view of the drug storage unit and the cavity according to the embodiment of this present invention;

FIG. 2 is a schematic view of the stopper separated from the housing according to an embodiment of the present invention;

FIG. 3 is a schematic view of the needle holder at the working position according to an embodiment of the present invention.

FIG. 4 a -FIG. 4 c are schematic views of the principle of the unlock rod releasing the needle holder according to different embodiments of the present invention;

FIG. 5 a -FIG. 5 b are respectively schematic views before and after the unlock rod releases the needle holder according to another embodiment of the present invention.

DETAILED DESCRIPTION

As mentioned above, at present, during the infusion process of the existing drug infusion device, due to the imbalance of the internal and external pressure, or non-full and improper priming of the fluid path or all the air in the infusion needle cannot be exhausted in time during the infusion process, causing the air infused under the skin, which affects the health of the user and poses a safety risk.

In order to solve this problem, the present invention provides a needle mechanism module for drug infusion device, the needle mechanism module comprises a stopper, the stopper limits the position of the needle holder, when the needle mechanism module is at intermediate position, the front end is connected with the drug storage unit of the infusion device, to balance the internal and external pressures, when the infusion unit is activated, the drug can enter the infusion needle to prime the fluid path and exhaust all the air from the infusion needle, preventing air from being infused into subcutaneous, which eliminates safety hazards and improves user experience.

Various exemplary embodiments of the present invention will now be described in detail with reference to the drawings. The relative arrangement of the components and the steps, numerical expressions and numerical values set forth in the embodiments are not to be construed as limiting the scope of the invention.

In addition, it should be understood that, for ease of description, the dimensions of the various components shown in the figures are not necessarily drawn in the actual scale relationship, for example, the thickness, width, length or distance of certain units may be exaggerated relative to other structures.

The following description of the exemplary embodiments is merely illustrative, and is not intended to be in any way limiting the invention and its application or use. The techniques, methods and devices that are known to those of ordinary skill in the art may not be discussed in detail, but such techniques, methods and devices should be considered as part of the specification.

It should be noted that similar reference numerals and letters indicate similar items in the following figures. Therefore, once an item is defined or illustrated in a drawing, it will not be discussed further in the following description of the drawings.

FIG. 1 a is a schematic view of a part of the structure of the infusion device according to an embodiment of this present invention. FIG. 1 b is a schematic view of the needle mechanism module taken along the section line A-A′ in FIG. 1 a . FIG. 1 c is a schematic view of the drug storage unit 1110 and the cavity 30 according to the embodiment of the present invention.

As shown in FIG. 1 a and FIG. 1 b, the infusion device of the embodiment of the present invention includes a housing 100 where the infusion unit is provided. The needle mechanism module, arranged on the housing 100, is used to fixedly place the infusion needle 130, making the drug flow infused under the skin of the patient.

As shown in FIG. 1 b, the needle mechanism module includes an infusion needle 130 and a needle holder 120. The infusion needle 130 is fixedly placed on the needle holder 120. The infusion needle 130 includes a front end 130 a and a rear end 130 b, both of which extend out of the needle holder 120. The front end 130 a is used to communicate with the opening 20 of the drug storage unit 1110, while the rear end 130 b is used to inserted under the skin of the patient.

As shown in FIG. 1 c, the housing 100 is further provided with a cavity 30 including a first outlet 31 and a second outlet 32. The first outlet 31 is in sealed communication with the opening 20. Here, the sealed communication means that the cavity 30 and the drug storage unit 1110 are in communication with each other through the opening 20 and the first outlet 31 without drug leaking. The second outlet 32 is sealed by an elastic seal 40. When the front end 130 a pierces the elastic seal 40, the infusion needle 130, the cavity 30, the opening 20 and the drug storage unit 1110 are in communication. Therefore, the drug can enter the infusion needle 130 from the drug storage unit 1110 to the rear end 130 b or be infused under the skin of the patient.

Please continue to refer to FIG. 1 a, FIG. 1 b and FIG. 1 c , in the embodiment of the present invention, the needle holder 120 has three positions: an initial position, an intermediate position, and a working position. Among them, the intermediate position is set between the initial position and the working position. Since the infusion needle 130 is fixed on the needle holder 120, in the embodiment of the present invention, the needle mechanism module also has the above three positions.

Preferably, in the embodiment of the present invention, when the needle holder 120 is at initial position, the front end 130 a does not pierce the elastic seal 40, so it is not communicated with the second outlet 32. When the needle holder 120 reaches the intermediate position or the working position, the front end 130 a pierces the elastic seal 40 communicating with the second outlet 32. At this time, the drug, along the cavity 30 and the infusion needle 130, flows from the drug storage unit 1110 to the rear end 130 b.

At the beginning, the needle holder 120 is at the initial position with the infusion needle 130 non-communication with the drug storage unit 1110. Therefore, the cavity of the infusion needle 130 is full filled with air. When leaving the factory, the non-communication between the infusion needle 130 and the drug storage unit 1110 can improve the flexibility of the setting position of the needle mechanism module, which optimizes the structural design of the infusion device.

After the needle holder 120 reaches the intermediate position, the front end 130 a pierces the elastic seal 40 in order to make the infusion needle 130 communicate with the drug storage unit 1110 to balance the internal and external pressures. At this time, when the infusion unit is activated, the drug can flow, along the infusion needle 130, to the rear end 130 b, to prime the fluid path and exhaust the air in the cavity of the infusion needle 130. Then, when the needle holder 120 reaches the working position, the rear end 130 b inserted under the skin to inject the drug into the body. Since the air in the infusion needle 130 has been exhausted earlier, no pressure difference, and no air will be infused under the skin when the needle holder 120 reaches the working position, thereby eliminating potential safety hazards.

In order to ensure that the needle mechanism module can reach different positions, the infusion device of the present invention is also provided with a first engaging portion 140 which is used to engage the needle holder 120 at the above-mentioned different positions. The first engaging portion 140 is one or a combination of hook, hole, blocks and slot. Preferably, in the embodiment of the present invention, the first engaging portion 140 is a hook.

Please continue to refer to FIG. 1 b, in the embodiment of the present invention, the needle holder 120 also includes a guide post 121. A guide cavity (not shown) is also provided in the housing 100 of the infusion device. The guide post 121 can move along the guide cavity, so that the needle holder 120 can be at different positions. The position where the needle holder 120 engaged with the first engaging portion 140 is located on the guide post 121, the side surface of the guide post 121 is provided with convexes or concaves 123, engaged with the first engaging portion 140 to limit the position of the needle holder 120. For example, when the needle holder 120 is engaged at position A, the needle holder 120 is at the initial position; and when engaged at position B, the needle holder 120 is at the intermediate position.

Please continue to refer to FIG. 1 a and FIG. 1 b , in the embodiment of the present invention, the infusion device further includes a stopper 110 which is arranged on the housing 100, used to limit the position of the needle holder 120. Therefore, the first engaging portion 140 is disposed on the stopper 110. Preferably, in the embodiment of the present invention, an engaging arm 112 is provided on the stopper 110. And the first engaging portion 140 is disposed on the engaging arm 112. The engaging arm 112 is engaged with the convexes or concaves 123 on the side surface of the guide post 121 to limit the position of needle holder 120, ensure the needle holder 120 was limited at the non-working position.

When the needle holder 120 is at the initial position, the first engaging portion 140 is engaged at position A. Directly pressing the top of the needle holder 120 with a finger makes the first engaging portion 140 engaged the guide post 121 at position B, so that the needle holder 120 reaches the intermediate position.

It should be noted that the needle holder 120 may not be provided with the guide post 121, but a structure capable of engaging with each other is provided on the side wall of the needle holder 120, which is not specifically limited here, as long as the needle holder 120 can reach different position.

Preferably, in the embodiment of the present invention, the use of the stopper 110 can only engage the needle holder 120 at the initial position and the intermediate position. In addition, the needle holder 120 cannot reach the working position due to the stopper 110, which can prevent the needle holder 120 from falling off due to movement, offer enough time to exhaust the air in the infusion needle 130, and prevent the infusion needle 130 from being touched or pressed by mistake and inserted into the skin, causing the imbalance of the internal and external pressure, or non-full and improper priming of the fluid path or the air is not exhausted or exhausted incompletely. At the same time, an auxiliary engaging portion 150 is provided on the housing 100, an auxiliary engaging part 122 is provided on the needle holder 120, the auxiliary engaging portion 150 and the auxiliary engaging part 122 communicated with each other to engage the needle holder 120 at position C, that is, to limit the needle holder 120 engaged at the working position. The auxiliary engaging part 122 or the auxiliary engaging portion 150 is one or a combination of hook, hole, block, or slot.

It should be noted herein that the cooperation between the auxiliary engaging part 122 and the auxiliary engaging portion 150 includes direct or indirectly engaging of the two, which will be described in detail below.

The auxiliary engaging part 122 may be provided on the guide post 121 or at other positions of the needle holder 120, which will not be specifically limited herein. Preferably, in the embodiment of the present invention, the auxiliary engaging part 122 is disposed under the top of the needle holder 120, as shown in FIG. 1 b.

A spring 160 is also provided in the guide cavity. As the spring 160 is provided, the needle holder 120 can pop-up and be automatically reset after the engagement between the auxiliary engaging part 122 and the auxiliary engaging portion 150 released, which optimizes the resetting process and facilitates the user's operation. When the needle holder 120 is in the working position, the spring 160 is compressed and provides resilience to the needle holder 120. Preferably, in the embodiment of the present invention, the spring 160 is sleeved on the bottom end of the guide post 121. However, due to the auxiliary engaging part 122 and the auxiliary engaging portion 150 are engaged with each other, the resilience of the spring 160 cannot be released. In another embodiment of the present invention, the bottom of the guide post 121 directly contacts and presses the top of the spring 160.

FIG. 2 is a schematic view of the stopper 110 separated from the housing 100 according to an embodiment of the present invention.

The stopper 110 of the embodiment of the present invention includes a slider 111. The housing 100 is provided with a sliding groove 101 where the slider 111 is arranged. The stopper 110 can slide along the sliding groove 101 to engage or release the needle holder 120 more conveniently. Preferably, in the embodiment of the present invention, after sliding the stopper 110 to release the engagement of the needle holder 120, the stopper 110 can be removed from the housing 100, as shown in FIG. 2 .

Please continue to refer to FIG. 1 a and FIG. 2 , in the embodiment of the present invention, the thickness of the forward end 114 of the stopper 110 is less than the thickness of the backward end 115. It should be noted that the forward direction of the stopper 110 here refers to the direction of sliding toward the needle holder 120 to realize engagement with the needle holder 120. Correspondingly, the backward direction of the stopper 110 refers to the direction of leaving the needle holder 120 and releasing the engagement with the needle holder 120. The thickness of the forward end 114 and the backward end 115 of the stopper 110 may be abruptly changed in the form of steps, as shown in FIG. 1 a and FIG. 2 , or may be gradually changed, which is not specifically limited here, as long as the thickness of the forward end 114 is smaller than the thickness of the backward end 115. Due to the difference in thickness between the forward end 114 and the backward end 115, when sliding the stopper 110 forward to realize the limit engagement and backward to release the limit engagement, it fits more closely with the fingers, which saves more effort and improves the user experience.

Therefore, the working principle of the needle holder 120 reaching these three positions in the embodiment of the present invention is as follows. At the beginning, the infusion device is not attached to the skin surface, the first engaging portion 140 engaged with the guide post 121 at position A, so the needle holder 120 is at the initial position. At this time, the front end 130 a does not pierce the elastic seal 40, so that the infusion needle 130 is not in communication with the drug storage unit 1110. Then, directly pressing the top of the needle holder 120 with a finger makes the first engaging portion 140 engaged with the guide post 121 at position B, so the needle holder 120 is at the intermediate position. Although the infusion device is still not attached to the skin surface, the front end 130 a of the infusion needle pierces the elastic seal 40 making the infusion needle 130 communicate with the drug storage unit 1110 to balance the internal and external pressures. Therefore, when the infusion unit is activated, the drug can flow in the cavity of the infusion needle 130, prime the fluid path and exhaust air in the infusion needle 130. At this position, the rear end 130 b does not extend or slightly extends out of the housing 100. Then attach the infusion device on the skin surface. And slide the stopper 110 backward, the first engaging portion 140 leaving the position B, to release the engagement of needle holder 120. Continue to press the top of the needle holder 120 so that the second engaging portion 150 engaged with the guide post 121 at position C. Therefore, the needle holder 120 is at the working position, and the rear end 130 b inserted under the skin. Obviously, the infusion needle 130 is communicated with the drug storage unit 1110, and the drug can be injected under the skin.

FIG. 3 is a schematic view of the needle holder 120 at the working position according to the embodiment of this present invention.

An shown in FIG. 3 , the auxiliary engaging part 122 engaged with the auxiliary engaging portion 150, the needer holder 120 reaches the working position, the spring 160 is compresses. At that time, the drug can be injected under the skin from the drug storage unit through the infusion needle 130. As mentioned above, when the needle holder 120 is at the working position, the rear end 130 b is inserted into the skin. The infusion device needs to be replaced when the drug is exhausted. If the rear end 130 b does not retract into the infusion device when the infusion device is torn off from the skin surface, the end of the rear end 130 b is likely to scratch the skin, causing additional trauma and poor user experience. Therefore, as the spring 160 is provided in the embodiment of the present invention, the rear end 130 b of the infusion needle can be retracted into the housing 100 before the infusion device torn off from the skin, which avoids scratching the skin and improves user experience.

Preferably, in the embodiment of the present invention, the needle mechanism module of further includes an unlock hole 170 and an unlock rod 180 (as shown in FIG. 1 a and FIG. 2 ). The opening of the unlock hole 170, arranged on the needle holder 120 or on the housing 100, serves as a working channel of the unlock rod 180 to release the needle holder 120. The unlock rod 180 can be inserted into the unlock hole 170. Pushing the unlock rod 180 to release and reset the locked needle holder 120, whose working principle will be described in detail below.

The unlock rod 180 can be provided in the infusion device, or a separate component attached to the product purchased by the user. Preferably, in the embodiment of the present invention, the unlock rod 180 is disposed on the stopper 110, such as at one end of the stopper 110 (as shown in FIG. 1 a and FIG. 2 ). In another embodiment of the present invention, the unlock rod 180 is provided as a separate component in the product of the infusion device.

FIG. 4 a -FIG. 4 c are schematic views of the unlock rod 180 releasing the needle holder 120 in different embodiments of the present invention. FIG. 4 a is a schematic view of the needle mechanism module taken along the section line B-B′ in FIG. 3 .

The mode for forcing to release and reset the needle holder 120 in the embodiment of the present invention includes a pop-up mode, that is, the releasing and resetting process of the needle holder 120 requires the resilient force of the spring 160. The principle of releasing and resetting the needle holder 120 is as follows. The front end of the unlock rod 180, inserted into the unlock hole 170, acts on the auxiliary engaging portion 150. And then, while pushing the unlock rod 180, the end of the auxiliary engaging portion 150 is tilted and moves a certain distance, thereby releasing the engaging of the auxiliary engaging part 122. Therefore, under the action of the resilience of the spring 160, the needle holder 120 is released and reset from the working position to the initial position, thus, the back end 130 b of the infusion needle moves out of the skin, or even retracts into the infusion device.

Obviously, according to the position of the auxiliary engaging portion 150, the opening of the unlock hole 170 may also be provided on the top or side wall of the housing 100. Preferably, in the embodiment of the present invention, the opening of the unlock hole 170 is provided on the top of the infusion device housing 100.

As shown in FIG. 4 b, the opening of the unlock hole (not shown) is provided on the side wall of the housing 100. Similarly, while the unlock rod 180 is being inserted into the unlock hole, the top end of the auxiliary engaging portion 150 is pushed to move to one side, thereby releasing the engaging of the auxiliary engaging portion 150 with the auxiliary engaging part 122, and also releasing the needle holder 120.

It should be noted that the opening of the unlock hole 170 can also be provided on the top of the needle holder 120. Similarly, pushing the unlock rod 180 into the unlock hole 170 can make the end of the auxiliary engaging portion 150 move a certain distance, as shown in FIG. 4 c.

FIG. 5 a -FIG. 5 b are schematic views of before and after the unlock rod 280 releases and resets the needle holder 220 according to another embodiment of the present invention.

The mode for forcing to release and reset the needle holder 220 also includes a pushing mode, that is, the releasing and resetting process of the needle holder 220 does not rely on the elastic force of the spring, instead by continuously pushing the unlock rod 280.

Preferably, in the embodiment of the present invention, the needle mechanism module further includes a locking lever 290. The auxiliary engaging portion 250 is a slot while the auxiliary engaging part 222 is a hole or a slot provided on side surface of the guide post 221. The auxiliary engaging portion 250 cooperates with the auxiliary engaging part 222 through the locking lever 290 to realize the locking of the needle holder 220, that is, the auxiliary engaging portion 250 and the auxiliary engaging part 222 are indirectly engaged, and the locking lever 290 is used as a transition component. The locking lever 290 includes a first end and a second end, and its fulcrum is set on the housing 200 and between these two ends. The first end of the locking lever 290 is movably arranged inside the auxiliary engaging part 222. Since the movable range of the needle holder 220 is limited, the first end of the locking lever 290 is always located inside the auxiliary engaging part 222. Before the needle holder 220 is released and reset, the second end of the auxiliary engaging part 222 and the auxiliary engaging portion 250 are engaged with each other to limit the needle holder 220 in the working position, as shown in FIG. 5 a.

As shown in FIG. 5 b, the principle of releasing and resetting the needle holder 220 by the unlock rod 280 is as follows. After the unlock rod 280 is inserted into the unlock hole 270, pushing the unlock rod 280, the second end of the locking lever 290 is forced, therefore, the end of the auxiliary engaging portion 250 moves to its one side due to the force received from the second end of the locking lever 290, thus, making the locking lever 290 unlocked, and making the needle holder 220 reset and released. Obviously, because there is no spring inside the infusion device, the user needs to continue to push the unlock rod 280. Using the principle of leverage (the arrows in FIG. 5 b indicate the direction of the force F and the releasing and the resetting direction D of the needle holder 220, respectively), the user releases and resets the needle holder 220, which makes the back end 230 b of the infusion needle remove out of the skin.

In order to facilitate the user to apply a small force on the unlock rod 280 to reset the needle holder 220, preferably, in the embodiment of the present invention, the opening of the unlock hole 270 is provided on the top of the needle holder 220, and the longitudinal directions of the unlock hole 270 and the guide post 221 are parallel to each other.

It should be noted that, in another embodiment of the present invention, a spring may also be provided inside the infusion device. At this time, the user only just needs to release the second end of the locking lever 290 without continuously pushing the unlock rod 280. Therefore, under the action of the spring's resilience, the needle holder 220 can be release and reset, which is similar with the foregoing.

In summary, the present invention provides a needle mechanism module for drug infusion device. The needle mechanism module comprises a stopper, the stopper limits the position of the needle holder, when the needle mechanism module is at intermediate position, the front end is connected with the drug storage unit of the infusion device, to balance the internal and external pressures, when the infusion unit is activated, the drug can enter the infusion needle to prime the fluid path and exhaust all the air from the infusion needle, preventing air from being infused into subcutaneous, which eliminates safety hazards and improves user experience.

While the invention has been described in detail with reference to the specific embodiments of the present invention, it should be understood that it will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims. 

1. A needle mechanism module for drug infusion device, comprising: an infusion needle, provided with a front end and a rear end; a needle holder, provided with at least an auxiliary engaging part, wherein the infusion needle is arranged on the needle holder, when the needle holder is at a working position, the rear end is inserted into a skin, and the front end is connected to a drug storage unit of the infusion device; an auxiliary engaging portion, arranged within the infusion device, engaged with the auxiliary engaging part to limit the needle holder at the working position; and a stopper, arranged on a housing of the infusion device, when the needle holder is at a non-working position, the stopper limits a position of the needle holder.
 2. The needle mechanism module for drug infusion device of claim 1, wherein the needle holder includes a guide post which moves along a guide cavity that is provided in the housing of the infusion device.
 3. The needle mechanism module for drug infusion device of claim 2, wherein the auxiliary engaging part is arranged on the guide post or under a top of the needle holder, and the auxiliary engaging part or the auxiliary engaging portion comprises a hook, a hole, a block, or a slot.
 4. The needle mechanism module for drug infusion device of claim 1, wherein a slider is provided on the stopper while the housing is provided with a sliding groove, the slider is arranged in the sliding groove, and the slider slides along the sliding groove to make the stopper engage or release the needle holder.
 5. The needle mechanism module for drug infusion device of claim 4, wherein at least one engaging arm is provided on the stopper.
 6. The needle mechanism module for drug infusion device of claim 5, further comprising a first engaging portion, wherein the first engaging portion is provided on the engaging arm to engage with the needle holder to limit the position of the needer holder.
 7. The needle mechanism module for drug infusion device of claim 6, wherein a side surface of the guide post is provided with convex or concave, the engaging arm engaged with the convex or concave to limit the position of the needle holder.
 8. The needle mechanism module for drug infusion device of claim 7, wherein a thickness of a forward end of the stopper is smaller than a thickness of a backward end of the stopper.
 9. The needle mechanism module for drug infusion device of claim 8, wherein the stopper is provided with an unlock rod.
 10. The needle mechanism module for drug infusion device of claim 9, it further comprising a unlock hole, wherein an opening of the unlock hole is provided on the top of the needle holder, a top of the housing, or a side wall of the housing, the unlock rod release engagement of the auxiliary engaging part and the auxiliary engaging portion through the unlock hole.
 11. The needle mechanism module for drug infusion device of claim 10, wherein the opening of the unlock hole is provided on the top of the needle holder, and longitudinal directions of the unlock hole and the guide post are parallel to each other.
 12. The needle mechanism module for drug infusion device of claim 3, wherein a mode to release and reset the needle holder comprises a pop-up mode or a pushing mode.
 13. The needle mechanism module for drug infusion device of claim 12, it further comprising a spring, arranged in the guide cavity, which is compressed by the needle holder when the needle holder is in the working position.
 14. The needle mechanism module for drug infusion device of claim 12, it further comprising a locking lever, wherein the auxiliary engaging part is a hole or a slot, a first end of the locking lever is movably arranged inside the auxiliary engaging part while a second end of the locking lever is engaged with the auxiliary engaging portion, a fulcrum of the locking lever is arranged between the first end and the second end of the locking lever, and the second end is pushed by the unlock rod to move a distance to release engagement of the auxiliary portion and the locking lever and release the needle holder. 